Within the organic fraction of atmospheric particles, so-called "humic-like substances" (HULIS) make up a significant fraction. The chemical composition of this fraction is largely unknown. Separation techniques such as revered phase liquid chromatography (RP-LC) or capillary electrophoresis do not allow for a successful separation of this complex fraction. This is why the present projects suggests to apply a 2-dimensional separation based on polarity (RP-LC) and molecular size (size exclusion chromatography). The two dimensions (columns9 will be coupled offline and fractions will be collected to determine total organic carbon (TOC), UV-Vis absorbance, and elemental compositions of characteristic fragments by time-of-flight mass spectrometry (TOFMS). Particles from different environments will be sampled (European background, Asian megacity, rural location with strong biomass burning influence), in order to identify and compare patterns within the 2-dimensional polarity vs. size space. In addition, the results of the offline characterization will be compared with data from an online aerosol mass spectrometer. The results of this project are expected to allow for a better understanding of concentration, composition and possible sources of the important HULIS fraction of atmospheric particles.
DFG Programme
Research Grants
